1. Field of the Invention
The present invention relates to a clothes dryer, and more particularly, to a control method of a clothes dryer and an apparatus thereof.
2. Description of the Conventional Art
Generally, a clothes dryer rotates clothes inside a drum by rotating the drum, and generates heat at a heater mounted therein. As a drying fan inside the clothes dryer is rotated, a low temperature-little moisture air passes through the heater thus to be converted into high temperature-little moisture air.
The clothes dryer heats clothes by introducing the high temperature-little moisture air into the drum. As the clothes are heated, vapor is generated and thereby the high temperature-little moisture air is converted into high temperature-much moisture air. The high temperature-much moisture air is condensed by an internal condenser thus to be converted into a low temperature-little moisture air with the moisture thereof removed. Then, the low temperature-little moisture air passes through the heater as the drying fan is rotated thereby to be converted into high temperature-little moisture air. That is, the clothes dryer dries clothes by repeatedly performing the process for heating clothes by introducing air into the drum. Also, the clothes dryer stops the operation of the heater when the clothes are completely dried, and drives only a motor thereby to cool the clothes so that a user can easily take out the clothes from the drum.
FIG. 1 is a view showing a sectional surface of a clothes dryer in accordance with the conventional art.
As shown, the clothes dryer comprises: a body 11; a drum 24 installed in the body 11 and accommodating clothes to be dried; a suction duct 14 formed at a rear surface of the drum 24 and supplying air into the drum 24; a suction fan 15 installed at the suction duct 14; and a motor 17 for driving the suction fan 15 and the drum 24. A door 21 for putting/taking laundry C in/out of the drum is installed at a front surface of the body 11, and an air passage 12 for introducing external air is formed at a rear surface of the body 11.
An air discharge passage 20 and an air discharge duct 18 for discharging air inside the drum 24 outwardly are formed at the front surface of the drum 24. The suction duct 14 for sucking air inside the body 11 and thereby supplying into the drum 24 is installed at a rear surface of the drum 24, and a suction passage 16 is formed at a lower portion of the suction duct 14. A heater 13 for heating air is installed at the suction passage of the suction duct 14. A plurality of lifts 23 for upwardly lifting the laundry C to be dried and dropping are formed in the drum 24.
Hereinafter, a front cover 22 positioned at the front surface of the drum 24 when the door 21 is closed will be explained with reference to FIG. 2.
FIG. 2 is a view showing a rear surface of the front cover of the clothes dryer.
As shown, an inlet port 25 for putting/taking the laundry C into/out of the drum is formed at the front surface of the drum 24, and the front cover 22 for covering the inlet port 25 is coupled thereto. A dryness degree sensor 19 for sensing a dryness degree of the laundry C inside the drum 24 is installed at a lower portion of the front cover 22.
Hereinafter, the dryness degree sensor 19 will be explained with reference to FIG. 3.
FIG. 3 is a view showing a dryness degree sensor of the clothes drier.
As shown, the dryness degree sensor 19 senses a dryness degree of the laundry C on the basis of a difference of current values varied according to a moisture contain degree of the laundry C at the time of contacting the laundry C. The dryness degree sensor 19 is composed of a pair of electrode sensors arranged in parallel with a certain interval. That is, as a moisture amount contained in the laundry is increased, a current value of the dryness degree sensor 19 is increased, and as a moisture amount contained in the laundry is decreased, a current value of the dryness degree sensor 19 is decreased. According to this, a dryness degree of the laundry can be sensed on the basis of the current value.
FIG. 4 is a view showing a dryness degree representative value calculated based on a signal of the dryness degree sensor of FIG. 2.
As shown, a dryness degree representative value is calculated on the basis of a signal value (dryness degree value) generated from the dryness degree sensor 19 as the laundry C to be dried is dried. On the basis of the calculated representative value, a heating value of the heater 13 and a driving of the drum 24 are controlled.
However, in a control method of the conventional clothes drier, a dryness degree representative value was calculated by equally applying the same sampling rate or the same number of samples even if a dryness graph showing a dryness degree of an initial period A that the laundry C contains much moisture and a dryness degree of a later period B that the laundry C relatively contains less moisture is non-linearly varied. Therefore, a dryness degree of the laundry C inside the drum 24 is not precisely reflected on the dryness degree representative value, thereby lowering a reliability of the dryness degree representative value.
Also, since a dryness degree of the laundry C is not precisely reflected on a dryness degree representative value, the laundry C is over-dried thus to have a damage or a deformation and a power consumption of the clothes drier is increased.
As aforementioned, in the conventional clothes drier, a dryness degree representative value is calculated by applying the same sampling rate or the same number of samples, and a heating value of the heater is controlled on the basis of the dryness degree representative value. According to this, the clothes are over-dried or an under-dry phenomenon that an operation for drying the clothes is stopped is frequently generated. Also, the heater is continuously operated even under a state that the clothes are completely dried, thereby consuming unnecessary much power.
Details of the conventional clothes drier are disclosed in U.S. Pat. No. 6,449,876 issued in Sep. 17, 2002.